Contact means



Get. 1'1, 1938. o. HAMPTON z-:r AL 2&32585 CONTACT MEANS Filed June 4,1954 v 3 sheets-sheet 1 2/ wald@ ZL/V 5mg f, Z2 ATTORNEY.

Oct. 11, 1938. w. o. HAMPTON Er AL 2,132,685 l CONTACT MEANS 5sheets-sheet 2` Filed June 4, 1934 ATTORNEY.

Oct, 11, 1938. w. o. HAMPTON ET A1. 13??685 CONTACT MEANS 1 m El?ZNVENTOR r ATTORNEY.

Patented Oct. 11, 1938 UNITED STATES PATENT OFFICE CONTACT MEANS IllinApplication June 4, 1934, Serial No. 728,992

4 Claims.

Our invention relates to contact means and contact devices and isparticularly concerned with novel and improved structures of contacttreads such as may be employed in traffic counting and traffic controlsystems and the like.

The known contact devices of this character are of rather expensivestructure. They usually employ metallic contact strips or contact platesof desired length spaced from each other either depending on theresiliency of the metal or by separate spring means, and placed within arubber casing which is usually disposed in a metal cage or housingarranged for disposal within an excavation of corresponding size whichmay be provided in the pavement of a tramo lane.

Such structures may be generally speaking satisfactory but they exhibitdrawbacks aside from the expenses involved in their manufacture. Theyare bulky and cannot be placed on the pavement without endangering thesafety of the tramo. An excavation is therefore necessary in any caseWhere such contact devices of known Structure, as above intimated, areused. As far as the features of operation are concerned, this 25 mightnot necessarily indicate a handicap in a permanent installation. 'I'heonly effect will be the increased cost if it is assumed, of course, thatthe structure is technically as perfect as it can be made in any givencase. However, it will be 30 seen at once that the necessity forexcavating presents a serious drawback if a temporary use of such acontact device is contemplated, such as may be indicated in the case oftraic counts rather than permanent traflic control at any givenlocality. Neither should the many locations be ignored Where a temporaryexcavation is practically out of question, such as on a bridge or theapproach to a bridge, yet Where a trac count might be and usually is ofutmost im- 40 portance.

Our invention is designed to overcome the difculties and drawbacksbriefly intimated above and to produce a device of this character whichcan be manufactured and installed at less ex- 45 pense and which will atthe same time be more positive and more sensitive in operation and alsoadapted for more universal use. Some of the objects of our invention maybe briefly stated as follows:

One object of our invention is concerned with the structure of a contactdevice of this character employing a separate and removable contactmember proper which can be manufactured in quantities according to moreeconomical methods and, therefore, cheaper than is possible by (Cl.20G-86) using'contact means which must be designed and producedindividually for any given tread structure.

Another object has to do with a tread structure wherein a plurality ofcontact means may be employed either arranged for mutual cooperation and/or including spare contact means that might be connected in the circuitin case of trouble. f

A further object may be found in the structure of a positively operatingContact device that can be employed, if desired, for temporary purposeswithout the necessity of excavating the pavement.

Still another object relates to provisions in conjunction with such adevice for readily exchanging the contactor or contact means properWithout the necessity of dismantling the entire apparatus.

Other objects are concerned with improvements in detail parts; withincorporating in our invention a structure permitting the use ofpractical and economical metal casings including a metal cover; withstructures for use in non-directional as well as in directional countingor traflic control systems; and with numerous other improvements whichWill appear from the detailed description rendered below with referenceto the drawings in which:

Fig. `1 shows the structure of the contactor or contact means proper;

Fig. 2 indicates one embodiment of our invention in its simplest form;

Figs. 3 to 9, inclusive, illustrate several embodiments of our inventionas it may be realized in non-directional heavy duty contact treaddevices;

Fig. 10 shows the embodiment of a device for relatively light duty;

Figs. 11 to 15, inclusive, illustrate our invention as applied tovarious structures primarily intended for use as directional Contacttread devices; and

Figs. 16, 17 and 18 show a contact tread device made in accordance withour invention and a diagram for explanatory purposes.

The invention will now be described in detail, first with reference tothe contact means proper or contact cable as illustrated in Fig. 1. Thiscontact cable is similar to the contact cable disclosed in the Britishpatent to Nagy, No. 272,893, but Will be briefly described herein toavoid the necessity of consulting said patent. f

Referring now to Fig. 1, the contact cable or contact device illustratedin this gure in plan View and partially in cross section comprises acentral metallic member indicated by the numeral II. Around this memberII which may be a metal wire are provided the wires I2 arranged tocontact member II and to form therewith the core of the device. Placedaround the core and helically disposed thereon may be the contact Wireor inner pole I3. The contact wire thus holds the core assemblyconsisting of member II and wires I2 in the position shown. In thespaces between the coils of the contact wire I3 is disposed theinsulation cushion I4. This cushion may consist of a strip of resilientinsulating material, such as rubber, in which may be embedded a wire I5for the purpose of facilitating the handling and placement of theinsulation cushion between the coils of the contact wire I3. Thecooperation of the insulation cushion I4 which rests on vthe wire coreI2 between the windings of the contact wire I3, as shown, producesrecesses such as indicated by the numeral I In other words, the contactwire I3 is now disposed between the coils formed by the insulationcushion Ill. Placed around the insulation cushion are Wires I'I aroundwhich is wrappedra covering cushion I8 as shown. The latter may becovered by a suitable fabric I9. Thus, the wires I'I are electricallyinsulated or isolated by the insulating cushion I from the contact wireI3 and thus from the coreV of the device. VThe core, composed of themembers II and I2 and including the conductor I3 forms one pole, and thewires Il form the other pole of the` device.

If it is assumed now that a pressure is exerted on the contactor deviceor contact cable shown in Fig. l at any place along its body, suchpressure will be transmitted from the covering fabric to the coveringcushionrIB and from there tothe wires Il. The latter will press on theinsulation cushion It and will compress the same, and nally the contactbetween the outer pole Il and the inner pole conductor I3 will beestablished by the wires I'I engaging the helical contact wire I3. Thiscondition is illustrated in Fig. 1 by the arrow at the right end of thedrawing. If it is assumed that current is connected to the inner pole ofthe device composed of the members II, I2 and conductor I3 and also tothe outer pole il, a circuit will now be established at the placeindicated by the arrow in Fig. l, namely, where the pressure is exertedon the device. The inner pole and the outer pole will be in electricallyconductive engagement. The same effect will be produced responsive topressure at anyplace along the body of the device shown in Fig. l.

The contactor or contact cable described above is employed in ourcontact tread device and takes the place of the usual contact meanstherein. It will be realized that the dii-ference between using acontact cable or means, such as above described,

'and the orthodox contact strips or contact plates extending throughoutthe length of a contact tread of this character is a basic one. Ourdevice is more sensitive and will respond to the application of lesspressure than is necessary for eiecting the operation of relativelyrigid contact plates. Our device will therefore respond quicker and willnot necessitate a wide eiective contact area as is the case withpreviously known devices of this character. As far as the manufacture ofthe contact-cable or contactor means above described is concerned, ascontrasted with the manufacture of metallic strips or plates, it may bestated that the contactV cable described herein may be manufacturedaccording to well known quantity provirtues.

duction methods in the cable manufacture. The contactor may be providedin bulk on cable drums, and the desired l-engthsmay be simply cut offand employed in our novel contact tread, whereas in case of contactVtreads employing metallic strips or plates, it is necessary to cut andfit these contact plates or strips individually for each desired treadstructure. Another advantage resides in the fact that this contactdevice is exible throughout its length.

It will be apparent from the above explanation that the use of acontactor, such as shown in Fig. l, in a contact tread for traic controlin itsy broadest meaning represents the realization of animportant'object of our invention, namely, the use ina contact tread fortrafc control and the like, of a contact means comprising a centrallydisposed pole and a companion pole placed around said pole and spacedtherefrom by means of a resilient member or members.

Oneof the simplest applications of our invention is indicated in Fig. 2.In this case the contact tread device consists merely of the rubbercasing 20V in which is disposed the contactor of the construction shownin Fig. 1 and designated in Fig. 2 by the numeral 2 I The insertion ofthe contactor 2l in the rubber casing 2d may be effected by theprovision'of a longitudinal slot at the bottom of the casing 2i), asindicated by the Jreference numeral 22. All that is necessary formounting th-e contactor 22 in its flexible casing 2&3 is transversedistortion and stretching of the casing so as to open the slot 22 and toforce the contact cable through the slot until it assumes the positionshown.

Such a structure as described above has several In the first place, itis easily manufactured and can be furnished at reasonable cost. It isalso easily transported to any location where its use is desired.Wherever temporary installations, for example for effecting trafficcounts for supervisory or statistical purposes and the like are desired,the embodiment shown in Fig. 2 will serve well. It can be placed on thepavement without necessitating any excavation. The counting device ormetering device will be connected in a circuit including the inner andthe outer pole, respectively, of the Contact means ZI, and the devicewill be ready for operation. Vehicles will roll over the device withoutany hazard to the safety and, in rolling over the same, the pressureapplied by the weight of the vehicle and the impact on the device willproduce the engagement of the outer pole with the inner pole andtherefore a closure of the metering or counting circuit. The overalldepth of this device may be veryrlittle, for example, between Y1/2 and linch, or somewhat more depending on the purpose, and it will be realizedthat such an object on the pavement does not represent any hazard to thesafety of the trailicat any speed.

It should be noted at this point that the simple device described abovewith reference to Fig. 2 represents a considerable improvement overprior constructions of this kind, being composed essentially of twounitary members, each of which is flexible, and permitting speedyassembly as wellr as ercient application. Y

Of course, a device such as shown in Fig. 2, although very well adaptedfor temporary purposes, will perhaps not meet the requirements V of aheavy duty permanent installation without some modification. It shouldbe observed, however, that prior devices of this character do notcontemplate a contact tread composed mainly of two parts, that is, of aself-contained flexible contactor proper comprising contact memberswhich re insulated from each other and encased in an insulationcovering, disposed within a flexible unitary casing, whereby thearrangement of the contactor within the flexible casing is accomplishedwithout any mounting or dismounting operations necessitating the use oftools. Neither do devices of this character hitherto known contemplate acontact tread which is flexible in its entire structure. The importanceof this feature is not to be underestimated since it facilitatestransportation of the contact device, and since this is an importantitem in the case of temporary application of the device.

An embodiment of a heavy duty permanent contact tread structure isillustratedv in cross section in Fig. `3. This structure is similar tothe device as illustrated in Fig. 2 in that a rubber tread member 34transmits pressure to the contact cable 32. It differs, however, inseveral constructional details, being a reinforced heavy duty treaddevice for permanent service rather than for temporary application aspreviously described. 'I'he structure includes the steel base 3l havinga longitudinal groove centrally formed along its upper side in which thecontact cable 32 is disposed, as shown. The restoring spring member 33may be provided on the base plate 3| to support the rubber tread 34 sothat little or no pressure is normally exerted on the contact cable 32.The edges of the rubber tread member 34 are protected and held securelyin place against the base plate 3| by means of the steel angle bars 35which may be clamped down by screws such as 36. A tight seal thereforeexists between the base 3| and the tread member 34 whereby the contactcable 32 is preserved from deterioration and obstructing foreign matteris excluded from the chamber formed over the base plate by the springmember 33.

The contact assembly or tread may be firmly A secured to the pavement bymeans of bolts (not shown) passing through holes in line with the holesthrough which clamping screws 36 pass. The base member 3| may also bemade wider than shown or may be provided with suitable ears orextensions for accommodating attaching means. It should be noted,however, that this device as well as any of the contact tread devicesdisclosed herein can be successfully employed without permanentattachment to the pavement.

In operation, the Wheel or tread of a vehicle will pass over the treadstructure of Fig. 3 and the weight on the rubber tread member 34 willcause a downward pressure to be applied through the restoring springmember 33 to the contact cable 32. The two poles of the cable (seeFig. 1) will make electrical contact with each other, as previouslydescribed. Since the cable 32 is disposed in a groove, as shown, it isnot damaged by a heavy weight passing over the structure. The restoring.spring member 33 can be depressed only until it makes intimate contactwith the main body of the base plate 3|. In other words, the deflectionof member 33 is definitely limited to the requirements of operationwithin safe limits of reliable performance. The base and the groove inwhich the contact cable is disposed in conjunction with the member 33which is arranged to compress the cable for effecting its operationrepresent essentially means for preventing the crushing of the cable.This structure will permit only such compression, regardless of theforce applied, as will be well within the performance characteristics ofthe contactor. This feature, it should be noted, is to be found in allthe structures disclosed in this application.

'When the weight isv removed from the device,

the tread member 34 is restored to the position shown due .to itsinherent resiliency and also due to the action of the member 33 actingas a restoring means. The two poles of cable 32 then break electricalcontact with each other, thereby initiating and/or terminating, as thecase may be, the signal or current impulse or impulses used foractuating the corresponding recording, indieating and/or signallingapparatus provided for cooperation with the tread structure.

It is to be not-ed particularly that the permanent structure of Fig. 3is well suited for installationon the surface of a roadway. Therefore,it may be used not only on ordinary street or road pavement, but also onbridges, approaches kto bridges and the like, where the installation ofthe conventional flush-type of contact tread, which requires excavation,is not ordinarily feasible because of the character of the underlyingroadway or pavement structure. This tread device on account of its lowand compact structure will serve also as a portable device to be usedfor temporary purposes such as required for observation of trafiic orthe like, and when used thus it will not ordinarily be found necessaryto secure it tothe pavement.

In operation, should the contact cable in the Vstructure of Fig. 3develop a fault, the cable may be withdrawn from the device at one endthereof and readily replaced by a new one without in any way disturbingthe remaining portions of the structure, as the cable rests relativelyloosely in the groove provided on the base plate 3|. In the event,however, that removal of the tread cover and of member 33 should berequired or desired, the screws 36 may be removed along one side of thestructure to permit the tread 34 and the spring or plate member 33 to belifted to free lthe contact cable 32 for inspection or replacement.Obviously the spring member 33 may be repaired or replaced by a new oneat such time. The term spring member is used for convenience sake:Member 33 is not a spring in the ordinary sense, but is merely asuitable curved member, preferably made from springy or resilientmaterial. Its function is to actuate as well as to protect the contactorand to assist in the restoration of the tread or cover of the device.

Referring now to Figs. 4 to 9,y inclusive, these figures show in crosssection modifications of the structure of Fig. 3.

A feature of the structure of Fig. 4 is that it may be assembled ofstandard steel stock with a minimum of forming and/or machiningoperations. The contact cable 42 is disposed on the base plate 4| in thegroove formed by the two .protection or spacer plates 44 which are pref-`cable 42. If desired, these members 45 may be made of resilientmaterial such as rubber. Their `function is to support and to space thecover member properly and to protect the Contact cable operatively aspreviously noted. This function caribe accomplished by the use of eitherrigid metallic or of resilient members 45 interposed be- 35 tween thecover and the base of the device. The sloping edgesof the tread or covermember 43 are firmly secured to the base assembly by screws 46 wherebythe entire assembly isreinforced. The openings in the cover provided forthe screws may be somewhat slotted if desired. A suitable gasket (notshown) maybe provided to secure the contact seal between the treadmember 43 and the base assembly. Effective operation of the contactcable 42 anywhere along the length of the device is secured whenthecentral portion of the tread Ymember'lS is pressed downward under theweight of the wheel of the passing vehicle or generally responsive topressur-e applied to it. It is understood, of course, that the covermaterial is somewhat resilient.

The structure illustrated in Fig. 5 is similar to the structure in Fig.4 in that it may be assembled of iiat stock material but differs in thesurface of the tread cover which in this instance is curved, and inother structural details as pointed out below.

The protection or spacer plates 54 may be welded together and secured tothe base slab 5| in the position shown, forming a longitudinalprotecting groove in which maybe disposed the contact cable 52. Themetal tread or cover member 53 is curvedly and angularly formed asshown. It lies on the rounded outer edges of the upper protection plates54 and in contact with the sloping machined outer edges of the basemember 5|. The screws 56 clamp the base member and the tread memberfirmly together, the desired spacing being provided by the rubber strips55 which yhold the tread member resiliently in position and provide aneffective seal. sure is applied to the tread member 53, for example, inresponse to the contacting of a passing 'vehicle, the curved portion ofthe tread member is temporarily flattened out, compressing the contactcablev 52 so that the two poles thereof come into temporary electricalco-ntact as previously discussed with reference to Fig. 1. It should beobserved that this structure also excludes crushing of the contact cabledue to the spacer and protecting means which limit the motion of thecover tread.

The modification illustrated in Fig. 6 is similar -to the preferredconstruction illustrated in Fig. 3

in that a curved tread surface is provided by the rubber tread member 64which may be clamped Abetween the base 6I and the angular clampingstrips 65 by the screws 66. The restoring spring member 63 underlies thetread member 54 throughout the entire width thereof, being held firmlyagainst the base member 6|. A suitable gasket (not shown) may be placedunder each outer flat section of the restoring member 63 to provide thedesired seal. The spacing and protecting strips 6l may be welded inplace to provide a groove for cable 62 and a support for a portion ofthe spring member in normal position. They will also act to stop thedownward movement of the tread assembly when the contact cable 32 isdepressed sufciently to make electrical contact in response to pressureapplied to the device.

The cross section illustrated in Fig. 7 is broken away at a point to theright of the central line. Features of this embodiment are that arelatively heavy spring tread member '|3 is supported only at its outeredges and that the groove formed by the spacing of the stop andprotecting strips 14 is sufliciently wide to accommodate a plurality ofcontact cables 12. One cable may be When presconnected Yfor use; in thecorresponding circuit and the others may be reserved to take the placeof spare cables to be used in the event that a breakdown occurs in thecable which is at any time in use.Y A plurality of these cables may alsobe used simultaneously in the same or in separate signalling circuits,if desired. It should be noted that the designation signalling circuitsor control system and equivalent expressions are used and applied hereinto denote broadly systems employing such vehicle actuated contacttreadsregardless of their particular structure, purpose and/or specificperformance.

The strips 'i4'and 'l5 may be secured by welding or the like to the baseas indicated. The support strips 15 may be of stock suiciently thick tosupport the tread 13 at such a distance from the base 1| that thecontact cables. 12 lie relatively loosely between base 1| and. the lowersurface of tread member i3. Screws 16 hold the tread 'I3 firmlyinposition,.the seal being eiected by means ofk suitable gaskets ifdesired. When pressure vehicular or otherwise is applied to the tread13, the central portion ythereof will be deflected or flexed and presseddownwardly causing each of the. cables 'l2V to be compressed'temporarilyinto effective electrical operating position. This tread structure willbe well suited for operation where heavy vehicle trafiic, for example,freight traffic is predominant.

The modification illustrated in Fig. 8 is similar to the one shown inFig. '7 but is distinguished by the feature that the tread member 83 isformed of a flat steel plate without formed edges while the approachslope is formed on either side by the successive set-back of the members8|, 85 and 83. The welded points of members 85 in relation to the basemember 8| are indicated in the drawings. This provides an extremelyeconomic and yet reliable construction. A gasket 8l may be used tofurnish the seal. The gasket may be disposed as shown, between the tread83 and the upper spacer strip or plate 85. The groove between the stopstrips is made wide enough to accomodate a plurality of contactcables82, if desired. Only one of these contact cables is shown in position.

In Fig..9, arubber tread member 93 is provided. The unique structure,however, renders unnecessary the provision of a restoring spring membersuch as 33 or 83 shown in the Figs. 3 and 6 respectively. The edges ofthe rubber tread member 93 are clamped between strips 91 and the spacingstrips 95 which may be welded to the base 9| as indicated. An effectiveseal is thus provided. It is also to be noted that the tread member 93lies directly on the stop members 94 which have rounded edges and whichmay be welded to the base 9| as indicated. When the wheel of a vehiclepasses over the tread 93, the unsupported central portion lying overcontact cable 92 is depressed to cause the two poles of the contactcable 92 to beforced into electrical engagement. vThe insulatingcovering of the contact cable as discussed in connection with Fig. 1 inconjunction with the manner of placing the contact cable in operativeposition between the members 94 prevent damage to the contact cableresponsive to the pressurev applied to the' device, regardless of theload within the operating limits of the corresponding system.Thus,'while considerable 'pressure cannot do any damage, only relativelylight pressure is actually required for operating the device. It shouldalso be considered in this connection that the downward displacementdoes not increase proportionately with the load because of the greatlyadded force required to displace a stretched membrane still further asis well known.

In Fig. 10, there is illustrated incross section a modiiicationespecially developed for light duty, that is to say, for operation atsuch points where trame is relatively light. A minor thoroughfarecrossing a major highway presents such kan occasion. Numeral |Irepresents a tubing which may be made of attened stainless steel or thelike. Rubber members |03 lie within the tube |0I and leave space for thecontact cable |02 which is disposed between them. Brackets such as |04spaced at desired intervals along the length of the tube may be employedfor holding the tube to the roadway, being secured by screws |05. Whenpressure is exerted on this device, for example, when a wheel of avehicle passes overV the tube |0I, the tube will be compressed slightlyandv in turn will compress and thereby actuate the contact cable |02.'I'his tendency is increased by virtue of the resulting compression ofthe rubber members |03. In this way the cable |02 is deflnitely andeffectively actuated by direct compression of the tube |0| as well as bythe resulting lateral compression of the compressed members |03. Whenthe vehicle has passed, the parts concerned will immediately resumenormal position. It will be appreciated that this embodiment can beproduced very economically for use in locations not demanding a heavyduty'structure.

As previously mentioned, Figs. 11 to 15, inclusive, illustratemodifications oi' our invention intended for use where directionaloperation is indi cated, for example, as contact devices operatingselectively with regard to trafiic direction. However, certain featuresof these devices may also be desirable and may be applied innon-selective or non-dircctional contact tread structures. The termdirectional as used herein denotes a device which will produce differentsignals or cause different operations, or wherein different conductorsare actuated responsive to pressure applied to the device from one orfrom the other side thereof, in short, a device arranged todifferentiate as to the direction of force, i. e., in this case,direction of traffic. Conversely, the term-"non-directiona1-is used todenote such an embodiment of our invention which will be actuated orwill cause actuation of other apparatus in the same way regardless ofthe direction from which the actuation initiates.

In Fig. ll, the inverted member II'I represents the tread member whichmay be welded to the base slab I Il to which the centrally located stopbar Ila is secured, for example by-welding. The base may be attached tothe roadway by means of screws such as I |0. Contact cables |I2 and H3of the structure illustrated in Fig. 1 are disposed alongside of thestop bar H4. The resilient spacers l which may be of rubber or the likelie to the left of cable |I2 while similar spacers IIG are disposed tothe right of cable IIB. It should be noted that there is a slightclearance space between stop bar ||4 and the lower surface oi the treadmember to permit a slight downward motion of the tread member responsiveto pressure applied to it'. This clearance space, however, is notsufhcient to permit enough perpendicular downward movement of the treadmember II'I to operate either of the cables tiated from the left andproceeding substantially horizontally to the right, when the object, forexample, the wheel of a vehiclestrkes the tread member at the left sidethereof, this tread member will be flexed and compressed toward theright by the horizontal thrust imparted by the wheel as it rolls up overthe edge of the tread member. This impact and motion squeezes the rubberspacers ||5 against the contact cable ||2 to effect its electricalactuation, while the space containing cable |23 and spacers H6 istemporarly and momentarily enlarged. This difierentiation it is to benoted is made possible by the partitioning effect of the stop bar ormember I4. As the object rolls along the center of the tread member, thesame will be depressed slightly in a wave motion tending to crowd therubber spacers ||5 still tighter against the cable |I2 and compress itstill further and to bring its poles into firmer electrical contact.Throughout the movement of a wheel over the tread in a given direction,the directional thrust will continue. It should be considered that thedevice is rather narrow, making the stopping of a wheel thereon unlikelyand in practice virtually impossible. However, as previously mentioned,the stop H limits the downward movement of the central portion of memberI in case a very slowly. mov ing vehicle should pass over the device sothat the cable I3 is not compressed perpendicularly to a sufilcientextent so as to bring its poles into electrical engagement. Such a caseis, however, more of a theoretical nature with little, if any, practicalsignicance or consequence.

As the wheel of a vehicle continues to roll across the tread, the abovementioned directional compression wave moves on to the right, tending tocrowd the rubber spacers ||5 to the right and still further removepressure rom contact cable H3. The directional contact is thusaccomplished for the actuation of the associated indicating signallingor recording equipment as the case may be. The normal position will beresumed when the lateral pressure motion ceases, that is, when the wheelof a vehicle leaves the device at the right side thereof.

In the above described way a Wheel rolls across the tread structure andactuates only one of the two contact cables, namely, in the assumedcase, only the left contact cable H2. When a wheel rolls across thetread structure from right to left, the above noted initial horizontalthrust and the subsequent wave motion are from right to left, causingcompression of the spacers IIB and actuation of contact cable H3 whilethe cable I2, which is sheltered by the stop bar I I4, is notelectrically actuated.

In Fig. l2, the heavy stop bar I 22 may be welded to the base |2| whilethe angle bars` |23 and |24 lie on either side of the stop bar to formducts for the selectively operable contact cables |29 and |30,respectively. The ilat bars |25 and |25 form rests for cables |29 and|30, respectively. The edges of these bars should preferably be rounded.The tread member |21 overlics the assembly as shown. When the wheel of avehicle strikes the tread member |21 from the left, the impact shiftsthe tread member to the right, forcing the Vangle bar |23 to compressthe contact cable |29 suiciently for electrical engagement of its poles.It should be considered that the operation of the contact cable requiresvery little mechanical motion since the inner pole is separated from theouter pole merely by a fraction of an inch, in practice, less than 1A;of an inch in most cases,

depending, of course, on the structure of the cable. An inspection ofFig. 1 will show, hoW- ever, that only very little motion is requiredfor effective operation'. In the event of a heavy impact, the upperright edge of angle bar |23 will engage the stop bar |22, therebypreventing damage to contact cable |29. As the wheel passes over thetread member and proceeds to the right, the assembly assumes normalposition but the contact cable |38 is not effectively actuated sincethere is no impact from the right of the device. However, when a vehicleapproaches from the right and passes over the tread to the left, theshift is to the left side and therefore cable |30 Will'be actuated toaccomplish the corresponding contact operation. In this instance, thecable |29 will remain unaffected.

In Fig. 13, the cable tubes |33 and |34 are secured by welding or thelike to the heavy bar |3| to form the edges of the tread. The bar |3|may be secured to the pavement by means of screws such as |32. The tubes|33 and |34 may be longitudinally slit or split at |35 and |35 tofacilitatecompression thereof. The impact of a moving object at the leftof the device will compress tube |33 to effectively squeeze contactcable |31 while an impact from the right will compress the tube L34 tooperatecable |38.

In considering this operation it should be re-` membered that thedirectional actuation of these devices depends on the directional forceof vehicles operating in different directions of movement. Since themovement occurs in a horizontal plane, the directional force will behorizontal. The perpendicular components of this force will diminishwith increased speed and will come fullyinto play only when the vehiclestops. Now, since we have to consider mainly moving forces inconjunction with the tread devices of our invention, it is apparent thatwe have to take into consideration mainly the directional forcesthereof. If it is considered in addition that the size of the devicesmade in accordance with our invention may be considerably smaller thanthe customary sizes of known devices of this character, it will also beseen that'thev perpendicular components of the moving forces can beneglected for practical consideration.

In Fig. 14, the tubes |42 and |233 areY preferably of steel and weldedto the T-bar base Mi. As in the embodiment shown in Fig.Y 13, thedirectional wheel impact against either edge of this device is dependedupon for selective operation of cables |44 and |135, respectively. Dueto the momentary compression of the corresponding tubes |42 and |43 inresponse to a directional impact and since these tubes are not slotted,a momentary slight attening at the point of iinpact is depended upon forcontact cable compression. It is understood, of course, that slottedtubes or cable casings may be employed.

In the embodiment shown in Fig. 15, the strips |52 and |53 may be weldedor otherwise fastened to the heavy bar |5| to form the two ducts for thecontact cables |54 and |55. The selective ,operation of this embodimentis similar to that described in connection with Fig. 13. The resiliencyof the structure at the edges of the device where the contact cables aredisposed is utilized for effecting their operation.

Referring now to Figs. 16 to 18, they illustrate a modification of theinvention which is especially suitable for counting use on a highwaywhereon several cars may travel in different directions, or where one ormore cars travelling in one direction may cross the tread line at a timewhen one or more cars cross it coming from the other direction. Invorderto avoid interference or loss of accuracy of many counts on account ofsimultaneouscrossing of the tread or counting line, it is desirable thata separate contact cable be used for eachtraftlc lane. This, of course,could be accomplished by using an entirely different contact tread foreach lane; but this besides necessitating several treads placed in linerequires surface conduits or embedded conduits to connect the cables ofthe inner lane treads with the counting equipment at the roadside. Wehave, therefore, constructed a tread in which can be accommodated aplurality of cables, each provided for a separate traffic lane. Figs.1'1 and 18 illustrate such a multi-cable contact tread long enough toextend over several traffic lanes, wherein each cable is sensitive tovehicular contact in only one predetermined traic lane. Fig. 16 is anaccompanying diagram to be referred to subsequently and illustrating acertain point of operation in conjunction with the tread structure shownin Figs. 17 and 18.

Referring now to the device shown in cross section in Fig. 1'1, thesteel tread member |12 may befastened to the base |1| by means of screwssuchas |13. Sealing gasket means may be employed if desired. The basemay be machined or otherwise formed into the indicated cross sectionwith a central groove for supporting contact cable such as |18 and sideducts for accommodating other cables. Spacer and protection and/ or stopmembers may be employed and assembled with the base as described withprevious embodiments. The sides of the walls or projections forming thecentral groove are spaced suiciently below the bottom of the treadmember to allow a contact cable, such as |18 disposed in the centralgroove or duct, to be compressed and thereby electrically actuated whena vehicle passes over the tread. It should be noted that the sidegrooves or ducts are somewhat deeper than the central groove. Thisfeature combined with the fact that the downward motion is less alongthe sides of the tread than at the center prevents actuation of thecables such as |14 to |11, lying within the side grooves. The brackets|19 and |88 hold the cables in place near the outside of the sidegrooves in the least sensitive area of the device.

Now, upon examining Fig. 18, it will be seen thatit is'a somewhatdiagrammatic plane view of the structure of Fig. 17 with the treadmember or cover |12 removed but with the contact cables in place intheir respective positions in the base |1|. In the central groove ofthis device which represents the sensitive area thereof, will beprovided a number of contact cable sections, their placementcorresponding to the traffic lanes. Each contact cable section isconnected by conductors or cables disposed in the side grooves or in theleast sensitive area of the device with the outside, as indicated inFig. 18. It will, therefore, be seen that although there is a singletread structure provided to extend over several traffic lanes, thecontact cables are selectively operable in accordance with traffic laneWidths and prevailing conditions. For example, cable |14 lies in thecentral sensitive area groove for a distance corresponding to the widthof the right hand trafc lane but passes over to a side duct for theremaining distance. Similarly, each of the cables |15 to |18 issensitive to wheel pressure in only a single portion of the treadlength, lying in a side duct for the remaining portion. It is apparent,of course, that the sides of the central groove may be cut away atdesired spacings to permit the passage of the cables from the centralgroove to a side groove.

The dividing lines between traffic lanes are usually painted on thesurface of the pavement. It is a recognized fact, however, that thedrivers do not always observe the lane division lines but occasionallydrive along partly in one lane and partly in another whereby onevehicle, for example, the vehicle designated in Fig. 16 by the numeral|63 may cause two contact cables, for example, |16 and |11 to beactuated simultaneously. With a separate counting device connected toeach cable, such a vehicle would be registered twice, once on eachcounter provided for the corresponding lanes. However, the naturallyarising discrepancies of the traffic compensate for this contingency.For example, again considering Fig. 16, it may be observed that twoseparate vehicles, such as |6| and |62, may drive and contact a singlecontact tread |15 at the same time. One counting discrepancy in acertain traflic lane is therefore more or less compensated for and setoff by discrepancies occurring in another lane. In other words, while itis true that one car may simultaneously actuate two contact devices oftwo separate lanes, it is also true that a plurality of cars may andwill at times cause the operation of only one contact device in anotherlane. Directional features may, of course, be incorporated in thestructure and system shown in Figs. 16 to 18.

Numerous modifications will occur to those skilled in the art. We wish,therefore, to have it distinctly understood that we have shown anddescribed denite structures and embodiments of our invention for thesake of description rather than for the purpose of indicatinglimitations. Our invention is specifically pointed out in the appendedclaims and we intend to use and to apply all such features singly andcombined that fall within the scope and spirit of the claims.

What we claim as our invention is:

1. A contact device for use on a roadway in the path of vehiculartrafl'lc, said device comprising a housing member adapted to extendacross the roadway on the surface thereof, said member including a rigidbase and a pair of straight rigid spaced strips secured thereto forminga channel, a contact cable removably disposed in said channel, saidcable including two conductors normally separated from each other, and aresilient cover disposed on said strips and on said base and adapted tobe compressed by the wheels of a vehicle to compress said cable andeiect contact between the conductors thereof, said strips forming a stopfor the downward movement of said cover and determining the maximumextent of compression of said cable.

2. A contact device for use on a roadway in the path of vehicular trafc,said device comprising a base adapted to lie on the surface of the road-Way and having an open channel on top, a contact cable disposed looselyin said channel and projecting above the sides thereof, said cableincluding two conductors normally separated from each other, a flexiblecover substantially covering said base and the said channel with thecable contained therein, a pair of sloping side members clamping saidcover to said base, and a curved spring member inserted between thecover and base and serving to support the central portion of the coverabove the cable, said cover and spring member being adapted fordepression by the wheel of a vehicle to compress said cable and effectcontact between the conductors thereof at the point where the cable iscompressed.

3. In a contact device for operation by vehicular traffic, a housing, acontact cable disposed in said housing, said cable including twonormally separated conductors adapted to be brought into engagement bycompression of the cable responsive to passage of a vehicle, and meansin said housing permitting operative compression of said cable by thepassage of a vehicle in one direction and preventing operativecompression of said cable by the passage of a vehicle in the oppositedirection.

4. In a contact device for operation by vehicular traic, a housing, twoparallel contact cables enclosed in said housing, each cable includingtwo normally separated conductors which are adapted to be brought intoengagement by compression of the cable responsive to passage of avehicle, and means included in said housing for preventing operativecompression of one cable by a vehicle moving in one direction and forpreventing operative compression of the other cable by a vehicle movingin the opposite direction.

WELDON O. HAMPTON. ALDO E. NESSLER.

